Overall objectives are: 1) to define the mechanisms which regulate protein turnover in intestinal mucosa, 2) to investigate relationships between structure and function of intestinal brush-border proteins, 3) to study proteins involved in intestinal transport systems. Studies will be extended to human tissue as well as animal mucosa and, where applicable, to specific disease states. Presently projected studies include: investigation of the specific ensyme systems responsible for protein turnover; definition of the biochemical defect in lactase deficiency; isolation and characterization of intestinal alkeline phosphatase; study of calcium-binding protein and calcium absorption in uremia; development of brush-border enzymes within rats, with special attention to the assembly of the membrane.